src/java.desktop/unix/native/libpipewire/include/spa/node/io.h

/* Simple Plugin API */
/* SPDX-FileCopyrightText: Copyright © 2018 Wim Taymans */
/* SPDX-License-Identifier: MIT */

#ifndef SPA_IO_H
#define SPA_IO_H

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \addtogroup spa_node
 * \{
 */

#include <spa/utils/defs.h>
#include <spa/pod/pod.h>

/** IO areas
 *
 * IO information for a port on a node. This is allocated
 * by the host and configured on a node or all ports for which
 * IO is requested.
 *
 * The plugin will communicate with the host through the IO
 * areas.
 */

/** Different IO area types */
enum spa_io_type {
    SPA_IO_Invalid,
    SPA_IO_Buffers,        /**< area to exchange buffers, struct spa_io_buffers */
    SPA_IO_Range,        /**< expected byte range, struct spa_io_range (currently not used in PipeWire) */
    SPA_IO_Clock,        /**< area to update clock information, struct spa_io_clock */
    SPA_IO_Latency,        /**< latency reporting, struct spa_io_latency (currently not used in
                  * PipeWire). \see spa_param_latency */
    SPA_IO_Control,        /**< area for control messages, struct spa_io_sequence */
    SPA_IO_Notify,        /**< area for notify messages, struct spa_io_sequence */
    SPA_IO_Position,    /**< position information in the graph, struct spa_io_position */
    SPA_IO_RateMatch,    /**< rate matching between nodes, struct spa_io_rate_match */
    SPA_IO_Memory,        /**< memory pointer, struct spa_io_memory (currently not used in PipeWire) */
    SPA_IO_AsyncBuffers,    /**< async area to exchange buffers, struct spa_io_async_buffers */
};

/**
 * IO area to exchange buffers.
 *
 * A set of buffers should first be configured on the node/port.
 * Further references to those buffers will be made by using the
 * id of the buffer.
 *
 * If status is SPA_STATUS_OK, the host should ignore
 * the io area.
 *
 * If status is SPA_STATUS_NEED_DATA, the host should:
 * 1) recycle the buffer in buffer_id, if possible
 * 2) prepare a new buffer and place the id in buffer_id.
 *
 * If status is SPA_STATUS_HAVE_DATA, the host should consume
 * the buffer in buffer_id and set the state to
 * SPA_STATUS_NEED_DATA when new data is requested.
 *
 * If status is SPA_STATUS_STOPPED, some error occurred on the
 * port.
 *
 * If status is SPA_STATUS_DRAINED, data from the io area was
 * used to drain.
 *
 * Status can also be a negative errno value to indicate errors.
 * such as:
 * -EINVAL: buffer_id is invalid
 * -EPIPE: no more buffers available
 */
struct spa_io_buffers {
#define SPA_STATUS_OK            0
#define SPA_STATUS_NEED_DATA        (1<<0)
#define SPA_STATUS_HAVE_DATA        (1<<1)
#define SPA_STATUS_STOPPED        (1<<2)
#define SPA_STATUS_DRAINED        (1<<3)
    int32_t status;            /**< the status code */
    uint32_t buffer_id;        /**< a buffer id */
};

#define SPA_IO_BUFFERS_INIT  ((struct spa_io_buffers) { SPA_STATUS_OK, SPA_ID_INVALID, })

/**
 * IO area to exchange a memory region
 */
struct spa_io_memory {
    int32_t status;            /**< the status code */
    uint32_t size;            /**< the size of \a data */
    void *data;            /**< a memory pointer */
};
#define SPA_IO_MEMORY_INIT  ((struct spa_io_memory) { SPA_STATUS_OK, 0, NULL, })

/** A range, suitable for input ports that can suggest a range to output ports */
struct spa_io_range {
    uint64_t offset;    /**< offset in range */
    uint32_t min_size;    /**< minimum size of data */
    uint32_t max_size;    /**< maximum size of data */
};

/**
 * Absolute time reporting.
 *
 * Nodes that can report clocking information will receive this io block.
 * The application sets the id. This is usually set as part of the
 * position information but can also be set separately.
 *
 * The clock counts the elapsed time according to the clock provider
 * since the provider was last started.
 *
 * Driver nodes are supposed to update the contents of \ref SPA_IO_Clock before
 * signaling the start of a graph cycle.  These updated clock values become
 * visible to other nodes in \ref SPA_IO_Position. Non-driver nodes do
 * not need to update the contents of their \ref SPA_IO_Clock.
 *
 * The host generally gives each node a separate \ref spa_io_clock in \ref
 * SPA_IO_Clock, so that updates made by the driver are not visible in the
 * contents of \ref SPA_IO_Clock of other nodes. Instead, \ref SPA_IO_Position
 * is used to look up the current graph time.
 *
 * A node is a driver when \ref spa_io_clock.id in \ref SPA_IO_Clock and
 * \ref spa_io_position.clock.id in \ref SPA_IO_Position are the same.
 */
struct spa_io_clock {
#define SPA_IO_CLOCK_FLAG_FREEWHEEL    (1u<<0) /* graph is freewheeling */
#define SPA_IO_CLOCK_FLAG_XRUN_RECOVER    (1u<<1) /* recovering from xrun */
#define SPA_IO_CLOCK_FLAG_LAZY        (1u<<2) /* lazy scheduling */
#define SPA_IO_CLOCK_FLAG_NO_RATE    (1u<<3) /* the rate of the clock is only approximately.
                         * it is recommended to use the nsec as a clock source.
                         * The rate_diff contains the measured inaccuracy. */
    uint32_t flags;            /**< Clock flags */
    uint32_t id;            /**< Unique clock id, set by host application */
    char name[64];            /**< Clock name prefixed with API, set by node when it receives
                      *  \ref SPA_IO_Clock. The clock name is unique per clock and
                      *  can be used to check if nodes share the same clock. */
    uint64_t nsec;            /**< Time in nanoseconds against monotonic clock
                      * (CLOCK_MONOTONIC). This fields reflects a real time instant
                      * in the past. The value may have jitter. */
    struct spa_fraction rate;    /**< Rate for position/duration/delay/xrun */
    uint64_t position;        /**< Current position, in samples @ \ref rate */
    uint64_t duration;        /**< Duration of current cycle, in samples @ \ref rate */
    int64_t delay;            /**< Delay between position and hardware, in samples @ \ref rate */
    double rate_diff;        /**< Rate difference between clock and monotonic time, as a ratio of
                      *  clock speeds. */
    uint64_t next_nsec;        /**< Estimated next wakeup time in nanoseconds.
                      *  This time is a logical start time of the next cycle, and
                      *  is not necessarily in the future.
                      */

    struct spa_fraction target_rate;    /**< Target rate of next cycle */
    uint64_t target_duration;        /**< Target duration of next cycle */
    uint32_t target_seq;            /**< Seq counter. must be equal at start and
                          *  end of read and lower bit must be 0 */
    uint32_t cycle;            /**< incremented each time the graph is started */
    uint64_t xrun;            /**< Estimated accumulated xrun duration */
};

/* the size of the video in this cycle */
struct spa_io_video_size {
#define SPA_IO_VIDEO_SIZE_VALID        (1<<0)
    uint32_t flags;            /**< optional flags */
    uint32_t stride;        /**< video stride in bytes */
    struct spa_rectangle size;    /**< the video size */
    struct spa_fraction framerate;  /**< the minimum framerate, the cycle duration is
                      *  always smaller to ensure there is only one
                      *  video frame per cycle. */
    uint32_t padding[4];
};

/**
 * Latency reporting
 *
 * Currently not used in PipeWire. Instead, \see spa_param_latency
 */
struct spa_io_latency {
    struct spa_fraction rate;    /**< rate for min/max */
    uint64_t min;            /**< min latency */
    uint64_t max;            /**< max latency */
};

/** control stream, io area for SPA_IO_Control and SPA_IO_Notify */
struct spa_io_sequence {
    struct spa_pod_sequence sequence;    /**< sequence of timed events */
};

/** bar and beat segment */
struct spa_io_segment_bar {
#define SPA_IO_SEGMENT_BAR_FLAG_VALID        (1<<0)
    uint32_t flags;            /**< extra flags */
    uint32_t offset;        /**< offset in segment of this beat */
    float signature_num;        /**< time signature numerator */
    float signature_denom;        /**< time signature denominator */
    double bpm;            /**< beats per minute */
    double beat;            /**< current beat in segment */
    double bar_start_tick;
    double ticks_per_beat;
    uint32_t padding[4];
};

/** video frame segment */
struct spa_io_segment_video {
#define SPA_IO_SEGMENT_VIDEO_FLAG_VALID        (1<<0)
#define SPA_IO_SEGMENT_VIDEO_FLAG_DROP_FRAME    (1<<1)
#define SPA_IO_SEGMENT_VIDEO_FLAG_PULL_DOWN    (1<<2)
#define SPA_IO_SEGMENT_VIDEO_FLAG_INTERLACED    (1<<3)
    uint32_t flags;            /**< flags */
    uint32_t offset;        /**< offset in segment */
    struct spa_fraction framerate;
    uint32_t hours;
    uint32_t minutes;
    uint32_t seconds;
    uint32_t frames;
    uint32_t field_count;        /**< 0 for progressive, 1 and 2 for interlaced */
    uint32_t padding[11];
};

/**
 * A segment converts a running time to a segment (stream) position.
 *
 * The segment position is valid when the current running time is between
 * start and start + duration. The position is then
 * calculated as:
 *
 *   (running time - start) * rate + position;
 *
 * Support for looping is done by specifying the LOOPING flags with a
 * non-zero duration. When the running time reaches start + duration,
 * duration is added to start and the loop repeats.
 *
 * Care has to be taken when the running time + clock.duration extends
 * past the start + duration from the segment; the user should correctly
 * wrap around and partially repeat the loop in the current cycle.
 *
 * Extra information can be placed in the segment by setting the valid flags
 * and filling up the corresponding structures.
 */
struct spa_io_segment {
    uint32_t version;
#define SPA_IO_SEGMENT_FLAG_LOOPING    (1<<0)    /**< after the duration, the segment repeats */
#define SPA_IO_SEGMENT_FLAG_NO_POSITION    (1<<1)    /**< position is invalid. The position can be invalid
                          *  after a seek, for example, when the exact mapping
                          *  of the extra segment info (bar, video, ...) to
                          *  position has not been determined yet */
    uint32_t flags;                /**< extra flags */
    uint64_t start;                /**< value of running time when this
                          *  info is active. Can be in the future for
                          *  pending changes. It does not have to be in
                          *  exact multiples of the clock duration. */
    uint64_t duration;            /**< duration when this info becomes invalid expressed
                          *  in running time. If the duration is 0, this
                          *  segment extends to the next segment. If the
                          *  segment becomes invalid and the looping flag is
                          *  set, the segment repeats. */
    double rate;                /**< overall rate of the segment, can be negative for
                          *  backwards time reporting. */
    uint64_t position;            /**< The position when the running time == start.
                          *  can be invalid when the owner of the extra segment
                          *  information has not yet made the mapping. */

    struct spa_io_segment_bar bar;
    struct spa_io_segment_video video;
};

enum spa_io_position_state {
    SPA_IO_POSITION_STATE_STOPPED,
    SPA_IO_POSITION_STATE_STARTING,
    SPA_IO_POSITION_STATE_RUNNING,
};

/** the maximum number of segments visible in the future */
#define SPA_IO_POSITION_MAX_SEGMENTS    8

/**
 * The position information adds extra meaning to the raw clock times.
 *
 * It is set on all nodes in \ref SPA_IO_Position, and the contents of \ref
 * spa_io_position.clock contain the clock updates made by the driving node in
 * the graph in its \ref SPA_IO_Clock.  Also, \ref spa_io_position.clock.id
 * will contain the clock id of the driving node in the graph.
 *
 * The position clock indicates the logical start time of the current graph
 * cycle.
 *
 * The position information contains 1 or more segments that convert the
 * raw clock times to a stream time. They are sorted based on their
 * start times, and thus the order in which they will activate in
 * the future. This makes it possible to look ahead in the scheduled
 * segments and anticipate the changes in the timeline.
 */
struct spa_io_position {
    struct spa_io_clock clock;        /**< clock position of driver, always valid and
                          *  read only */
    struct spa_io_video_size video;        /**< size of the video in the current cycle */
    int64_t offset;                /**< an offset to subtract from the clock position
                          *  to get a running time. This is the time that
                          *  the state has been in the RUNNING state and the
                          *  time that should be used to compare the segment
                          *  start values against. */
    uint32_t state;                /**< one of enum spa_io_position_state */

    uint32_t n_segments;            /**< number of segments */
    struct spa_io_segment segments[SPA_IO_POSITION_MAX_SEGMENTS];    /**< segments */
};

/**
 * Rate matching.
 *
 * It is usually set on the nodes that process resampled data, by
 * the component (audioadapter) that handles resampling between graph
 * and node rates. The \a flags and \a rate fields may be modified by the node.
 *
 * The node can request a correction to the resampling rate in its process(), by setting
 * \ref SPA_IO_RATE_MATCH_ACTIVE on \a flags, and setting \a rate to the desired rate
 * correction.  Usually the rate is obtained from DLL or other adaptive mechanism that
 * e.g. drives the node buffer fill level toward a specific value.
 *
 * When resampling to (graph->node) direction, the number of samples produced
 * by the resampler varies on each cycle, as the rates are not commensurate.
 *
 * When resampling to (node->graph) direction, the number of samples consumed by the
 * resampler varies. Node output ports in process() should produce \a size number of
 * samples to match what the resampler needs to produce one graph quantum of output
 * samples.
 *
 * Resampling filters introduce processing delay, given by \a delay and \a delay_frac, in
 * samples at node rate. The delay varies on each cycle e.g. when resampling between
 * noncommensurate rates.
 *
 * The first sample output (graph->node) or consumed (node->graph) by the resampler is
 * offset by \a delay + \a delay_frac / 1e9 node samples relative to the nominal graph
 * cycle start position:
 *
 * \code{.unparsed}
 * first_resampled_sample_nsec =
 *    first_original_sample_nsec
 *    - (rate_match->delay * SPA_NSEC_PER_SEC + rate_match->delay_frac) / node_rate
 * \endcode
 */
struct spa_io_rate_match {
    uint32_t delay;            /**< resampling delay, in samples at
                     * node rate */
    uint32_t size;            /**< requested input size for resampler */
    double rate;            /**< rate for resampler (set by node) */
#define SPA_IO_RATE_MATCH_FLAG_ACTIVE    (1 << 0)
    uint32_t flags;            /**< extra flags (set by node) */
    int32_t delay_frac;        /**< resampling delay fractional part,
                     * in units of nanosamples (1/10^9 sample) at node rate */
    uint32_t padding[6];
};

/** async buffers */
struct spa_io_async_buffers {
    struct spa_io_buffers buffers[2];    /**< async buffers, writers write to current (cycle+1)&1,
                          *  readers read from (cycle)&1 */
};

/**
 * \}
 */

#ifdef __cplusplus
}  /* extern "C" */
#endif

#endif /* SPA_IO_H */